General Flashcards
Definition of density
Measure of mass per volume unit
Unit of density
kg/m^3
Definition of fatigue
Cracking due to repeated cyclic loading over time
Definition of elasticity
The material returning to its original shape after the deforming force is removed
Definition of strength
Resistance to deformation or how much stress can be withstood before breaking.
Definition of hardness
Resistance to penetration, wear or cutting actions
Definition of plasticity
Allows a material to be reshaped and keep it.
Definition of ductility
Allows a material to be stretched into thinner sections without breaking
Definition of Malleability
Allows the material to be stretched or shaped by force without breaking
Definition of toughness
Ability to be deformed without breaking
Definition of brittleness
Resistance to change of shape
Ability to break when hammered or deformed
Definition of conductivity
Ability to transmit heat or electricity
Definition of durability
Ability to withstand forces over time
What are the 3 stresses?
Tensile
Compressive
Shearing
Definition of tensile strength
Stretching forces that result in stress
Definition of compressive stress
Stress created by forces trying to squash/shorten an object
Definition of shearing stresses
Stresses created by shearing forces
Combined stresses combinations?
Tensile and shearing
Compressive and shearing
What is simple stress?
One of the 3 stresses acting alone
What is unit stress?
The amount of deformation on one dimension of a body compared to the original dimension’s size
What is poisson’s ratio?
Negative ratio of lateral strain and longitudinal unit strain for a material under longitudinal stress within the proportional limit
What is the elastic limit?
The point where a material can be deformed up to before it will no longer return to its original shape
What is the yield point?
The maximum stress before permanent deformation
What is a ferrous material?
A material containing iron
What is non ferrous?
A metal without any traces of iron
What is the ultimate tensile stress?
The maximum tensile stress that can be applied before breaking the material
What is the breaking point of a sample?
Modulus of elasticity:
Ratio of stress and strain
3 most important lightweight metals in the industry?
Aluminium and their alloys
Titanium and their alloys
Magnesium and their alloys
Structure of metals
Crystalline
Body centred cubic (BCC)
9 atoms, one in each corner and one on the centre
Face centred cubic
14 atom, one in each corner and one in the centre of each face
What metals are hexagonal close packed and how many atoms are there?
17 atoms Cobalt Magnesium Titanium Zinc
Best selection of a material
Best compromise between cost and properties
